Jane,
I think the first thing you should do is write up exactly what you want a Management company (MC) to do. This statement of work will be lay out clear expectations and be the basis for any contract you enter into. You may find out that you don't need an MC but may only need a bookkeeper or a property manager to oversee specific items (which can be other options to look into)
The second thing would be to send out a request for proposal (RFP) to various management companies along with your statement of work. This will allow the MC to propose to you how they would accomplish what you expect and what it would cost. To identify who to send the RFP to, check with neighbor Associations who have an MC and see what they like and don't like about the company they use.
Once you narrow the field down, you should check references and do research into the company (are there complaints about them on the internet, BBB ratings, etc.).
When your ready to sign, remember that contracts are negotiable prior to signing. Be willing to suggest changes to anything you don't like. If you like company A but prefer the price company B offers, don't be afraid to ask if Company A will match the price (just don't tell them the name of Company B). We actually saved $10,000 a year on our Trash/recycling contract doing this.
Here are some links that may help:
[SAMPLE] RFP for HOA Management Company from HOALeader
Subject: Property Management Interview Suggestions an past thread on this forum
Quackit homepage Homeowner Association Management Contracts from the Americanbar (legal site)
Here are various RFPs for MC from different HOAs:
REQUEST FOR PROPOSALS HOA MANAGEMENT REQUEST FOR PROPOSALS # 4332 Quackit homepage REQUEST FOR PROPOSALS FOR COMMUNITY ASSOCIATION MANAGEMENT SERVICES Hope this helps,
Tim